The Collaborative International Dictionary of English v.0.48:

Rare \Rare\ (r[^a]r), a. [Cf. Rather, Rath.]
   Early. [Obs.]
   [1913 Webster]

         Rude mechanicals that rare and late
         Work in the market place.                --Chapman.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rare \Rare\, a. [Compar. Rarer (r[^a]r"[~e]r); superl.
   Rarest.] [Cf. AS. hr[=e]r, or E. rare early. [root]18.]
   Nearly raw; partially cooked; not thoroughly cooked;
   underdone; as, rare beef or mutton.
   [1913 Webster]

         New-laid eggs, which Baucis' busy care
         Turned by a gentle fire, and roasted rare. --Dryden.
   [1913 Webster]

   Note: This word is in common use in the United States, but in
         England its synonym underdone is preferred.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rare \Rare\, a. [Compar. Rarer (r[^a]r"[~e]r); superl.
   Rarest.] [F., fr. L. rarus thin, rare.]
   1. Not frequent; seldom met with or occurring; unusual; as, a
      rare event.
      [1913 Webster]

   2. Of an uncommon nature; unusually excellent; valuable to a
      degree seldom found.
      [1913 Webster]

            Rare work, all filled with terror and delight.
                                                  --Cowley.
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            Above the rest I judge one beauty rare. --Dryden.
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   3. Thinly scattered; dispersed.
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            Those rare and solitary, these in flocks. --Milton.
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   4. Characterized by wide separation of parts; of loose
      texture; not thick or dense; thin; as, a rare atmosphere
      at high elevations.
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            Water is nineteen times lighter, and by consequence
            nineteen times rarer, than gold.      --Sir I.
                                                  Newton.
      [1913 Webster]

   Syn: Scarce; infrequent; unusual; uncommon; singular;
        extraordinary; incomparable.

   Usage: Rare, Scarce. We call a thing rare when but few
          examples, specimens, or instances of it are ever to be
          met with; as, a rare plant. We speak of a thing as
          scarce, which, though usually abundant, is for the
          time being to be had only in diminished quantities;
          as, a bad harvest makes corn scarce.
          [1913 Webster]

                A perfect union of wit and judgment is one of
                the rarest things in the world.   --Burke.
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                When any particular piece of money grew very
                scarce, it was often recoined by a succeeding
                emperor.                          --Addison.
          [1913 Webster]

WordNet (r) 3.0 (2006):

rare
    adj 1: not widely known; especially valued for its uncommonness;
           "a rare word"; "rare books"
    2: recurring only at long intervals; "a rare appearance"; "total
       eclipses are rare events"
    3: not widely distributed; "rare herbs"; "rare patches of green
       in the desert"
    4: having low density; "rare gasses"; "lightheaded from the
       rarefied mountain air" [syn: rare, rarefied, rarified]
    5: marked by an uncommon quality; especially superlative or
       extreme of its kind; "what is so rare as a day in
       June"-J.R.Lowell; "a rare skill"; "an uncommon sense of
       humor"; "she was kind to an uncommon degree" [syn: rare,
       uncommon]
    6: (of meat) cooked a short time; still red inside; "rare roast
       beef"

The Free On-line Dictionary of Computing (19 January 2023):

Réseaux Associés pour la Recherche Européenne
RARE

   (RARE) An association of national and international European
   networks and users.

   See also CCIRN.

   (1994-11-30)